In our U.S. Pat. No. 5,291,918 dated Mar. 8, 1994 and entitled SAFETY VALVE ACTUATOR ASSEMBLY, there is disclosed a safety valve actuator used for closing a gate valve in a flowline and a hydraulic circuit which schematically illustrates the flow of hydraulic fluid in the circuit.
Improvements have been made, however, to overcome some of the disadvantages of the apparatuses taught in the '918 patent. One disadvantage of such apparatuses is that no provision was made for pressure relief. It is possible for fluid in the control circuit to increase or decrease in volume as the ambient temperature increases or decreases and provision should be made to allow for pressure relief in the event that the components are required to handle the pressure created by the increased fluid volume.
Other advantages in the present invention will become apparent during the detailed description and explanation made hereafter.